Exploring New Characteristics: Using Deep Learning and 3D Reconstruction to Compare the Original COVID-19 and Its Delta Variant Based on Chest CT.

Purpose: Computer-aided diagnostic methods were used to compare the characteristics of the Original COVID-19 and its Delta Variant. Methods: This was a retrospective study. A deep learning segmentation model was applied to segment lungs and infections in CT. Three-dimensional (3D) reconstruction was used to create 3D models of the patient's lungs and infections. A stereoscopic segmentation method was proposed, which can subdivide the 3D lung into five lobes and 18 segments. An expert-based CT scoring system was improved and artificial intelligence was used to automatically score instead of visual score. Non-linear regression and quantitative analysis were used to analyze the dynamic changes in the percentages of infection (POI). Results: The POI in the five lung lobes of all patients were calculated and converted into CT scores. The CT scores of Original COVID-19 patients and Delta Variant patients since the onset of initial symptoms were fitted over time, respectively. The peak was found to occur on day 11 in Original COVID-19 patients and on day 15 in Delta Variant patients. The time course of lung changes in CT of Delta Variant patients was redetermined as early stage (0-3 days), progressive and peak stage (4-16 days), and absorption stage (17-42 days). The first RT-PCR negative time in Original COVID-19 patients appeared earlier than in Delta Variant patients (22 [17-30] vs. 39 [31-44], p < 0.001). Delta Variant patients had more re-detectable positive RT-PCR test results than Original COVID-19 patients after the first negative RT-PCR time (30.5% vs. 17.1%). In the early stage, CT scores in the right lower lobe were significantly different (Delta Variant vs. Original COVID-19, 0.8 ± 0.6 vs. 1.3 ± 0.6, p = 0.039). In the absorption stage, CT scores of the right middle lobes were significantly different (Delta Variant vs. Original COVID-19, 0.6 ± 0.7 vs. 0.3 ± 0.4, p = 0.012). The left and the right lower lobes contributed most to lung involvement at any given time. Conclusion: Compared with the Original COVID-19, the Delta Variant has a longer lung change duration, more re-detectable positive RT-PCR test results, different locations of pneumonia, and more lesions in the early stage, and the peak of infection occurred later.

Diabetic Human Adipose-Derived Stem Cells Accelerate Pressure Ulcer Healing by Inducing Angiogenesis and Neurogenesis.

Adipose-derived stem cells (ASCs) possess a well-characterized capacity to enhance cutaneous wound healing. However, many controversies exist regarding ASCs from diabetic patients (dASCs). No report exists on the administration of dASCs for the treatment of pressure ulcers. The aim of this study was to compare properties of dASCs and nondiabetic ASCs (nASCs). In addition, we studied if dASCs enhanced pressure ulcer healing in a rodent pressure ulcer model and investigated underlying mechanisms. We found similar expression of cell surface markers and characteristics in dASCs and nASCs, although dASCs exhibited decreased proliferation and osteogenic differentiation capacity and enhanced adipogenic differentiation capacity. dASCs had beneficial effects on chronic wound healing, though some aspects of their capacity were impaired. The ability of dASCs to promote nerve regeneration was not compromised. dASCs promoted pressure ulcer healing and improved healing by modulating inflammation, promoting angiogenesis and neuroregeneration, enhancing collagen deposition, and increasing re-epithelization. These data may provide a theoretical foundation for further clinical administration of ASCs for chronic wound healing in patients with diabetes.

[Effect of human adipose-derived stem cells on pressure ulcer healing in mouse].

Objective: To investigate the effect of human adipose-derived stem cells (hADSCs) on pressure ulcers in mouse. Methods: The subcutaneous adipose tissue from voluntary donation was harvested. Then the hADSCs were isolated and cultured by mechanical isolation combined with typeⅠcollagenase digestion. The 3rd generation cells were identified by osteogenic, adipogenic, chondrogenic differentiations and flow cytometry. The platelet rich plasma (PRP) from peripheral blood donated by healthy volunteers was prepared by centrifugation. The pressure ulcer model was established in 45 C57BL/6 mice by two magnets pressurized the back skin, and randomly divided into 3 groups ( n=15). The wounds were injected with 100 µL of hADSCs (1×10 6 cells) transfected with a green fluorescent protein (GFP)-carrying virus, 100 µL human PRP, and 100 µL PBS in hADSCs group, PRP group, and control group, respectively. The wound healing was observed after injection. The wound healing rate was calculated on the 5th, 9th, and 13th days. On the 5th, 11th, and 21st day, the specimens were stained with HE staing, Masson staining, and CD31 and S100 immunohistochemical staining to observe the vascular and nerve regeneration of the wound. In hADSCs group, fluorescence tracer method was used to observe the colonization and survival of the cells on the 11th day. Results: The cultured cells were identified as hADSCs by induced differentiation and flow cytometry. The platelet counting was significantly higher in PRP group than in normal peripheral blood group ( t=5.781, P=0.029). General observation showed that the wound healing in hADSCs group was superior to those in PRP group and control group after injection. On the 5th, 9th, and 13th days, the wound healing rate in hADSCs group was significantly higher than those in PRP group and control group ( P<0.05). Histological observation showed that compared with PRP group and control group, inflammatory cell infiltration and inflammatory reaction were significantly reduced in hADSCs group, collagen deposition was significantly increased, and skin appendage regeneration was seen on the 21st day; at each time point, the expression of collagen was significantly higher in hADSCs group than in PRP group and control group ( P<0.05). Immunohistochemical staining showed that the number of neovascularization and the percentage of S100-positive cells in hADSCs group were significantly better than those in PRP group and control group on the 5th, 9th, and 13th days ( P<0.05). Fluorescent tracer method showed that the hADSCs could colonize the wound and survive during 11 days after injection. Conclusion: Local transplantation of hADSCs can accelerate healing of pressure ulcer wounds in mice and improve healing quality by promoting revascularization and nerve regeneration.

[Propeller facial artery perforator flap for repairing defect after resection of skin malignant tumor at upper lip].

Objective: To explore the effectiveness of propeller facial artery perforator flap to repair the defect after resection of skin malignant tumor at upper lip. Methods: Between July 2012 and January 2017, 17 cases with skin malignant tumor at upper lip underwent tumor resection and the remained defect was repaired with propeller facial artery perforator flap. Among the 17 patients, 3 were male and 14 were female, with an average age of 57 years (range, 35-82 years). There were 5 cases of squamous cell carcinoma and 12 cases of basal cell carcinoma. The disease duration ranged from 4 months to 11 years with an average of 20 months. The tumor size ranged from 1.4 cm×0.3 cm to 3.1 cm×1.4 cm. The extended resection of the tumor tissue was performed according to the characters of tumor. According to the location, size, and shape of the defect and the position of facial artery perforator explored with Doppler ultrasonography, the propeller facial artery perforator flap was designed to repair the defect and partial donor site. The flap size ranged from 5 cm×2 cm to 7 cm×3 cm. The length of the perforator pedicle was 0.5-1.0 cm with an average of 0.8 cm. The defect at donor site was directly closed. Results: Cyanosis occurred in 3 cases of the distal flap after operation, then healing after symptomatic treatment. The remaining flaps survived successfully and the wound healed by first intention. Primary healing was obtained in the donor site. All the patients were followed up 6-36 months with an average of 18 months. The shape of the patient's upper lip was good and the scar on the donor site was unconspicuous. There was no lip deformity, ala nasi deflection, facial tension, entilation dysfunction, or recurrence of tumor during follow-up. At last follow-up, the results of self-evaluation were very satisfactory in 13 cases and satisfactory in 4 cases. Conclusion: Based on multiple advantages of good blood supply, large rotation range, aesthetic outcome, and slight injury of the donor site, propeller facial artery perforator flap is not only an optimal choice for repairing upper lip defect after resection of skin malignant tumors, but also can achieve good functional and cosmetic effectiveness.